What is bloom?

[gevalia]

All,

Could you guys enlighten a newbie on [natural] lens bloom? I've read a little but what I have read leaves me more confused. Is bloom actually fungus? What are the effects? What does it add to a photo if anything? I seek your wisdom oh wise ones.

[N Dhananjay]

I've seen the word bloom used in 2 ways. The first is to describe an oxidation on the surface of a lens. This acts very much like a coating and I believe it was noticing this that led to the idea of coating to increase transmission. The second meaning appears to refer to an effect like that produced by soft-focus lenses where the highlight areas diffuse into the shadow areas to produce an impression of bright light (but with more pleasing tonalities).

What you are referring to is probably the former. In that context, I believe bloom usually refers to oxidation and not fungus.

Cheers, DJ

[seawolf66]

if the lens has a blue style color to it , or it looks like some how a drop of gasoline got on it thats normal for older lens and your right its called "Blooming" as a matter of fact I started a thread on just that subject , but can not seam to find it , I am sure one of the more astute folks here will chime in on that subject :

[AutumnJazz]

Thin film interference?

[BarryS]

Bloom was an early term using for lens coating. I've attached a photo of a Ross projection lens from about 1947 and you can see it's labeled with the proprietary term "Rosskote" with "BLOOMED" in parentheses.

http://img208.imageshack.us/img208/4033/ross45inul6.jpg

[gevalia]

How do I care for (clean) a lens with natural bloom? Do I risk wiping it off the lens or is this not a concern? I realize that I need to be more aware of lens flare with an uncoated lens as well.

[Glenn Thoreson]

Bloom is a natural oxidation of minerals in some early glass. Not all glass will do it. It was an inspiration for early coating processes. Bloom can contain many colors and can be quite pretty to look at. Cleaning a "bloomed" lens can be a delicate operation if you don't want to damage the "coating". Try to not clean it at all, beyond using a lens brush. I you do need to be more agressive, put a couple of drops of cleaning solution on a clean cotton ball and gently wipe it. Follow up with a dry cotton ball to remove any haze left b the solution. The bloom is very easy to scratch. I have couple of really nice examples of advanced blooming.

[seawolf66]

here is a web site that may help explain it :

http://forums.dpreview.com/forums/readflat.asp?forum=1018&message=10046496

[Glenn Thoreson]

Lauren, your link isn't talking about what we're discussing here. It talks about a whole different issue, the way I read it. :D